The usual process to produce NiTi shape memory alloys is vacuum induction melting (VIM). Currently a new alternative process to produce NiTi shape memory alloys by rapid solidification structures called Melt Spinning has been studied. In this work, results of ribbons with a chemical composition Ti-55.2 Ni (wt %) alloy prepared by this method are presented. The ribbons are prepared at two different linear velocities: 30 m/s and 50 m/s. After that, samples are heat treated at 350 °C during 1 hour. The alloys are characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction. According to the cycled DSC test, transformation peaks are associated with the B2→R→B19´ transformation during cooling and B19´→R→B2 during heating, showing transformation in multi-peaks. The martensite B19´ start (Ms) is varying from 35 to 39°C and the martensite finish (Mf) from 15 to 21°C, 42-47°C for austenite B2 start (As) and 65-69°C for austenite finish (Af) approximately. All analyzed ribbons show very similar values of transformation hysteresis temperatures at 50% of transformation of around 28°C. In order to change solidification rate, linear velocity is varied during the melt spinning process. Results indicate that linear velocity affects directly the temperature of transformation. When the linear velocity is increasing, crystallographic Ti-rich precipitates are developed, but dendritic growth disappears, changing the microstructure and decreasing these transformation temperatures. Then changes in linear velocity can dramatically affect shape memory properties, and in this case a velocity of 50 m/s produces a more homogenous alloy.

In the framework of the successive 1991 and 2006 Waste Management Act, French government supported a very significant R&D program on partitioning and transmutation of minor actinides (MA). This program aims to study potential solutions for still minimizing the quantity and the hazardousness of final waste, by MA recycling. Indeed, MA recycling can reduce the heat load and the half-life of most of the waste to be buried to a couple of hundred years, overcoming the concerns of the public related to the long-life of the waste.

Within this framework, this paper aims to present the most recent progress obtained in CEA on the development of innovative actinide partitioning hydrometallurgical processes in support of their recycling, either in an homogeneous mode (MA are recycled at low concentration in all the standard reactor fuel) or in an heterogeneous mode (MA are recycled at higher concentration in specific targets, at the periphery of the reactor core). Recovery performances obtained on recent tests in high active conditions of the so-called GANEX and DIAMEX-SANEX process will be presented and discussed in light of the potential P&T scenarios. Finally, recent developments regarding the recycling of the sole Am will be presented as well as the results obtained on highly active solutions for this so-called EXAM process.

This set of results gives to the French government a portfolio of potential recycling processes which could be separately and progressively implemented if decided.

The complex admittance of the Si+/SiO2/Pentacene/Au (metal/oxide/pentacene) thin film junctions is investigated under ambient conditions. The results are compared with the ones obtained for the corresponding Si+/SiO2/Au junctions (i.e. a small part of the surface left free from pentacene) which constitutes the “reference” of our samples. This allows us to extract the “organic” part of the dielectric response from the whole spectrum. Our data clearly show that the admittance is decomposed in three main contributions. At low frequencies, a contribution attributed to proton diffusion through the oxide is seen. This diffusion is shown to be anomalous and is believed to be also at the origin of the bias stress effect observed in organic field effect transistors. At higher frequencies, two dipolar contributions are evidenced, attributed to defects located one at the organic/oxide interface or within the organic, and the other in the bulk of the oxide. These two dipolar responses show different dynamic properties that manifest themselves in the admittance in the form of a Debye contribution for the defects located in the oxide, and of a Cole-Cole contribution for the defects related to the organic.

Nanocrystalline diamond (NCD) films are prepared from Ar-rich/N2/CH4 and Ar-rich/H2/CH4 mixtures by microwave plasma-enhanced chemical vapor deposition, and further treated by microwave hydrogen and oxygen plasma exposures separately to enhance the wetting property. The hydrogen plasma treatment has small effect on the surface roughness, while the oxygen plasma treatment forms fine protrusions on the film surface. Results show that the wettability of the hydrogen plasma treated NCD film is nearly constant or little improvement as the polar component of the apparent surface free energy is close to the as-deposit NCD film. In contrast, the wettability of the oxygen plasma treated NCD film is improved dramatically such that the contact angle is reduced from 92º and 4.7º to almost 0º for water and 1-bromonaphthalene, respectively, and the polar component increases significantly to 34 mJ/m2. The low contact angle suggests that the film is considerably a cell adhesive friendly surface, which is essential in maintaining multicellular structure, and thus making it a favorable wetting surface for biological and biomedical applications.

The detection of heavy metals in subsurface strata currently requires tedious sampling procedures followed by laboratory analysis using techniques such as atomic absorption spectroscopy (AAS) or inductively couple plasma atomic emission spectroscopy (ICP-AES). These techniques are extremely accurate and capable of detecting very low concentrations of metal ions. The main drawback of these techniques is that they are time consuming, expensive to perform and not portable. A portable sensor capable of detecting metals ion in solution is highly desirable. Anodic Stripping Voltammetry (ASV) can be utilized as a reliable method for the trace detection of metal ions in water. In order to improve the sensitivity of the electrochemical sensor, conjugated polymer films can be coated on the surface of the glassy carbon working electrodes. Stable films of poly (3,4 ethylenedioxythiophene) [PEDOT] and polythiophene copolymer [PTCPTA] were electrochemically synthesized on the surface of a glassy carbon electrode. These polymer modified electrodes were utilized for the detection of cadmium in water. The sensors are capable of detecting trace concentrations of cadmium approaching the maximum contamination limits imposed by the Environment Protection Agency (EPA).

Synchrotron topography studies are presented of the behavior of growth dislocations and deformation-induced dislocations in 4H-SiC single crystals. The growth dislocations include those in threading orientation with line directions approximately along c with Burgers vectors of a, c, and n a+m c (where n and m are integers) while the deformation-induced dislocations include those with line directions confined to the basal plane with Burgers vectors of a and Shockley partial dislocations with Burgers vectors of 1/3<1-100> as well as those with line directions in the {1-100} prismatic planes with Burgers vectors of a. Processes leading to the nucleation of the growth dislocations are discussed as well as their deflection onto the basal plane during crystal growth in a reversible process. This latter process can lead to the conversion of segments of the deflected growth dislocations into deformation induced dislocations. In some cases this can lead to dislocation multiplication via the Hopping Frank-Read source mechanism and in others to the motion of single Shockley partial dislocations leading to Shockley stacking fault expansion. Studies are also presented of interactions between threading growth dislocations with c-component of Burger’s vector facilitated by climb processes which are mediated by interactions with non-equilibrium concentrations of vacancies. This can lead to reactions whereby complete or partial dislocation Burgers vector annihilation occurs.

Highly stable, organic-based barium titanate (BaTiO3) sols were developed by the low cost and straightforward “organosol”-precipitation and auto-combustion process of amorphous organic precursors. BaTiO3/CoFe2O4 nanocomposites with core/shell structures embedded in a BaTiO3 matrix were also obtained using this process. The particles are systematically characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analyses (TGA/DTA), infrared spectroscopy (IR) and by laser granulometry for particle size distribution determination.

Dislocation mediated mechanism of surface deformation due to localized stress and strain concentration near a void could give an explanation of field enhancement in conditions relevant to the design of rf accelerating structures of the Compact Linear Collider (CLIC). We have performed molecular dynamics simulations of a near surface void in copper under thermal stressing conditions. The von Mises strain was observed to be concentrated near the void surface with the maximum strain concentration factor of 1.9. To observe the activated slip-planes, we exaggerated the compressive stress to the extent that the dislocations were nucleated on the void surface at sites where von Mises strain was largest. Void depth and size were found to affect the dislocation nucleation. The nucleation was easier for larger voids and for voids which were closer to the surface.

We deposited copper oxides by rf magnetron sputtering from a 4N Cu-target at room temperature, varying the oxygen flux and keeping the argon flow constant. Dependent on the oxygen flux Cu2O, Cu4O3or CuO were synthesized. The different compounds were characterized by XRD. The dielectric functions of the oxides were determined by spectroscopic ellipsometry and show significant differences between the compounds. The electrical properties, like the carrier concentration, of each compound can be tuned by adjusting the oxygen flux. We discuss the structural, optical and electrical properties of the copper oxides in terms of phase purity and stoichiometry deviations.

We have synthesized core-shell 1D nanostructures by the Vapor-Liquid-Solid (VLS) mechanism. Gold (Au) was used as a catalyst and tin oxide (SnO) powder as a precursor; the growth temperature was of 600 °C. These structures were characterized by XRD, SEM, TEM, EDS, and PL. The nanowires have an average diameter of 20 nm and their lengths are of tens of micrometers; the core is tin dioxide (SnO2) with the tetragonal rutile structure and it has an average diameter of 12 nm; the shell is amorphous Sn of 8 nm average thickness. Photoluminescence measurements show a broad band in the 400-800 nm range. On the same growth process, SnO2 nanoparticles and a mixture of SnO2 rods and wires were also obtained, at 400 °C and 800 °C, respectively.

Epitaxial thin films of SrLaVMoO6 with an ordered double perovskite structure have been grown on (001) and (111) SrTiO3 substrates by magnetron sputtering. The optimized (111) film exhibited a clear (111) diffraction peak, which is a superlattice reflection of double perovskite unite cell, indicating clear B-site ordering. Temperature dependences of resistivity ρ show metallic behavior and transition point at 140~150 K, of which behavior is reminiscent of the electrical properties of materials showing long-range magnetic or antiferromagnetic order. XPS results of the Mo 3d core level spectra are discussed in terms of the B-site ordering and oxygen nonstoichiometry.

The dark current-voltage characteristics of PIN structures are studied and analyzed for PV samples as for integral device without taking account the performance of the different elements typically used in equivalent circuit model such as diode n-factor, shunt and series resistances. The contribution of all these elements is very important in the development of devices because they determine the performance characteristics. In this work we have studied and compared the temperature dependence of current-voltage characteristics in μc-Si:H and pm-Si:H p-i-n structures having approximately the same efficiencies with emphasis on their different electronic characteristics such as shunt (Rsh) and series (Rs) resistance, ideality factor (n), and the saturation current (Is), which give us some ideas on role of these elements. In the pm-Si:H cell it was observed that the Rs increases with the increase of the temperature in contrast to the μc-Si:H structures, where the series resistance reduces with temperature change from T = 300 up to 480K. In both the pm-Si:H and μc-Si:H samples Rshreduces with temperature change from 300 up to 480 K. The ideality factor in the pm-Si:H structure shows an increase, and in μc-Si:H a reduction, when temperature increases. Saturation current in both cases increases with temperature as it was expected. From the saturation current it was obtained the build-in potential. Analysis behavior of both saturation current and n-factor with temperature shows that build-in potential increases with temperature in the pm-Si:H, but reduces in μc-Si:H structure.

Tunable WDM converters based on amorphous SiC multilayer photonic active filters are analyzed. The manipulation of the magnitude is achieved through appropriated front and back backgrounds. Transfer function characteristics are studied. Results show that the light-activated device combines the demultiplexing operation with the simultaneous photodetection and self amplification of an optical signal. Depending on the wavelength of the external background and irradiation side, it acts either as a short- or a long- pass band filter or as a band-stop filter. A combinational logic function is mapped onto an active two stage optoelectronic logic circuit. An algorithm to decode the multiplex signal is established. An optoelectronic model supports the optoelectronic logic architecture.

We have succeeded in the rapid epitaxial growth of Si, Ge, and SiGe films on Si substrates below 670 ºC by reactive CVD utilizing the spontaneous exothermic reaction between SiH4, GeH4, and F2. Mono-crystalline SiGe epitaxial films with Ge composition ranging from 0.1 to 1.0 have been successfully grown by reactive CVD for the first time.

This technique has also been successfully applied to the growth of these films on silicon-on-glass substrates by a 20 - 50 ºC increase of the heating temperature. Over 10 μm thick epitaxial films at 3 nm/s growth rate are obtained. The etch pit density of the 5.2 μm-thick Si0.5Ge0.5 film is as low as 5 x 106 cm-2 on top. Mobilities of the undoped SiGe and Si films are 180 to 550 cm2/Vs, confirming the good crystallinity of the epitaxial films.

In the wake of the recent terrorist attacks, such as the 2008 Mumbai hotel explosion or the December 25th 2009 “underwear bomber”, our group has developed a technique (US patent #7368292) to apply differential reflective spectroscopy to the problem of detecting explosives in order to detect terrorist threats. Briefly, light (200-500 nm) is shone on a surface such as a piece of luggage at an airport or a parcel at a courier distribution center. Upon reflection, the light is collected with a spectrometer combined with a camera. A computer processes the data and produces in turn a differential reflection spectrum taken between two adjacent areas of the surface. This differential technique is highly sensitive and provides spectroscopic data of explosives. As an example, 2,4,6, trinitrotoluene (TNT) displays strong and distinct features in differential reflectograms near 420 nm. Similar, but distinctly different features are observed for other explosives such as RDX, PETN or ANFO. Our detection system uses a two dimension detector (CCD camera) which provide spatial and spectroscopic information in each of the two dimensions. By scanning (involving fixed optical equipment and scanning moving bags or parcels on a conveyor belt), the surface to be surveyed the system provide the spatial location of the potential threat. We present in this paper how our detector works and how it is applied to the problem of explosive screening for explosives at airports and mail sorting centers. Additionally, we will present the effect of the explosives morphology on the detection response. In particular we will evaluate the implication on the limit of detection of the instrument as well as discuss the sample morphology with respect to a realistic threat scenario.

Bismuth iron oxide BFO films were produced by the pulsed laser deposition technique. These films are a mixture of BiFeO3 ferroelectrical and Bi25FeO40 piezoelectrical phases. The ferroelectrical domain structure of these films was studied via contact resonance piezoresponse force microscopy (CR-PFM) and resonance tracking PFM (RT-PFM). The proportions of area of these BFO phases were derived from the PFM images. The ferroelectrical domain size corresponds to the size of the BiFeO3 crystals. The CR-PFM and RT-PFM techniques allowed us to be able to distinguish between the ferroelectric domains and the piezoelectric regions existing in the polycrystalline films.

Solid-oxide fuel cell (SOFC) performance depends greatly upon electrode design. The composite anode plays a critical role in fuel reforming, especially when hydrocarbons are included in the fuel mixture. Because direct observation of fuel reforming in a functioning SOFC is difficult, if not impossible, an alternative experimental configuration is needed to evaluate anode performance. The Separated Anode Experiment (SAE) is designed to isolate and study porous-media transport and heterogeneous reforming chemistry in SOFC anodes. Although the experiment does not incorporate a dense electrolyte membrane or a cathode, it is configured to replicate important aspects of anode behavior in a fully operational SOFC. The experiment is also designed to facilitate model-based interpretation of the results. Comparisons of two significantly different anode structures are used to illustrate the experimental and modeling capabilities.

Facile and direct synthesis of radiative VO2 (M) plate-like is reported. The snowflake material presents superstructures plate-like aggregate with an anisotropic orientation in shape governed by V2O5 and NaOH concentration giving high surface energy liable for chemical reactions with the medium. Pure crystalline VO2 (M) has been obtained with a complete hydrothermolysis of the precursor. The morphological, structural, elemental composition, crystallinity and vibrational bands of the powders were characterized by Powder X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Selected Area Electron Diffraction (SAED) and Fourier Transform-Attenuated Total Reflection (FTIR-ATR) infrared spectroscopy.

Erbium-Ytterbium codoped nanophosphor systems are explored for high efficiency upconversion. The NIR to visible upconversion from 1550 nm and 980 nm excitation are of particular interest to us for biomedical applications such as imaging, sensing, and photodynamic therapy. Variations in synthesis method and rare earth concentration are carried out in sodium, potassium, and transition metal based phosphor materials. The spectroscopic properties of the material dry and in biologically appropriate solution are taken. After bioconjugation, these particles will be used in a mouse model to demonstrate that cancer imaging with a near-infrared excitation source is possible.